Runtime Configuration Validation for Self-configurable Systems

International audienceRuntime configuration validation is a critical requirement if we are to build reliable self-adaptive systems. This paper describes a model-based approach that supports runtime validation of candidate configurations. The approach is based on MeCSV, a metamodel we propose, that allows a technologyneutral specification of systems' configurations and validity constraints. A constraint-checker relying on this specification verifies dynamically candidate configurations before their deployment. Experimental results with a messaging platform show viable validation overhead demonstrating the feasibility of the approach

A Model-based Framework for System Configuration Management

A system can be viewed from different perspectives, each focusing on a specific aspect such as availability, performance, security. Configurations reflect the manageable resources of the system, their attributes and organization which are necessary for the management of the system for each aspect. Thus, for management purposes a system is generally described through various partial configurations (also known as configuration fragments). To form a consistent system con-figuration, these independently developed configuration fragments need to be integrated together. The integration of configuration fragments is a challenging task. This is mainly due to over-lapping entities (different logical representations of the same system resource) in the configuration fragments and/or complex relationships among the entities of the different configuration fragments. At runtime the system may be reconfigured to meet certain/new requirements or in response to performance degradations. These changes may lead to inconsistency as some changes may violate the constraints between entities. Maintaining the consistency and adjusting the system configuration at runtime is another challenging task. In our research, we propose to handle these two important issues in an integrated manner. We define a model-based framework for configuration management. We use the Unified Modeling Language (UML) and its profiling mechanism for representing the configuration fragments. Using model weaving and model trans-formation techniques, we propose a solution for the integration of configuration fragments targeting specific system properties. To handle runtime changes, we propose a configuration validation and adjustment solution to check and preserve the consistency of the system configuration. We introduce a partial validation technique in which the runtime reconfigurations are checked against a reduced set of consistency rules instead of the complete set of rules and the reconfigurations are applied only if they are safe, i.e. they preserve the configuration consistency. For handling the changes that violate the consistency rules, we propose an adjustment technique to automatically resolve (if possible) the inconsistencies. This is achieved by propagating the changes in the configuration according to the system constraints following the possible impacts of the configuration entities on each other. Some heuristics are used to reduce the complementary changes and to limit the propagation. We evaluate the complexity of our adjustment technique and conduct experiments to evaluate its efficiency. The Service Availability Forum middleware is used as an application domain in the examples throughout this thesis; however the proposed solutions are applicable in more general settings. We present proofs of concepts using different technologies. We use the Eclipse Modeling Framework (EMF) and Papyrus for implementing the UML profiles. The Atlas Model Weaver (AMW) and Atlas Transformation Language (ATL) are used to integrate the configuration fragments, and we also use the APIs of the Object Constraint Language (OCL) in the Eclipse environment and the Microsoft Z3 constraint solver to develop a prototype tool of our partial validation and adjustment agents

Un cadriciel pour la vérification en ligne, générique, flexible et évolutive de configurations de systèmes communicants complexes

Les systèmes communicants complexes constituent une base fondamentale de la vie d'aujourd'hui. Ils supportent de plus en plus de services et d'usages critiques, essentiels tant aux entreprises et administrations qu'à la société en général. L'exemple-type est celui d'Internet avec l'ensemble de ses services et usages variés, architectures et média allant de petits équipements mobiles comme les smartphones aux systèmes critiques à grande échelle comme les clusters de serveurs et le cloud. Il devient dès lors indispensable d'en garantir le fonctionnement effectif et continu. Pour ce faire, une vision consiste en la mise en œuvre de systèmes de gestion autonomes et adaptifs, capables de reconfigurer dynamiquement et en permanence ces systèmes afin de maintenir un état de fonctionnement désiré face à des conditions opérationnelles, instables et de moins en moins prévisibles. Un frein à l'exploitation effective des solutions de reconfiguration dynamique réside dans le manque de méthodes et de moyens garantissant l'effectivité et la sûreté de ces changements dynamiques de configurations. La contribution générale des travaux de cette thèse fournit des concepts, des méthodes et des outils qui favorisent la mise en œuvre d'une vérification en ligne de configurations. Notre démarche pour construire ce cadriciel a consisté dans un premier temps à définir un langage de haut niveau dédié à la spécification et la vérification de configurations. Nous avons architecturé dans un deuxième temps, un service de vérification générique, flexible et évolutive at runtime capable de manipuler les concepts définis dans ce langage. Enfin, nous avons défini une architecture de composants intermédiaires d'intégration de l'existant. Ce cadriciel permet de supporter un processus de vérification opérationnelle de configurations qui commence, en phase de conception par une spécification rigoureuse de modèles de configurations, puis se poursuit en phase d'exécution du système de gestion à travers une vérification automatique de configurations basée sur ces modèles. Le cadriciel a fait l'objet d'un prototype que nous avons expérimenté sur une série de cas issus de deux contextes applicatifs différents : la vérification de configurations d'un middleware orienté messages dans un environnement JMX et la vérification de configurations de machines virtuelles dans un environnement CIM/WBEM (standards du DMTF). Les résultats ont montré la faisabilité de l'approche ainsi que la capacité du cadriciel à soutenir une vérification en ligne, flexible et évolutive de configurations favorisant l'intégration de l'existant.Complex networked systems are a fundamental basis of today's life. They increasingly sup- port critical services and usages, essential both to businesses and the society at large. The evident example is the Internet with all its services and usages in a variety of forms, architectures and media ranging from small mobile devices such as smartphones to large-scale critical systems such as clusters of servers and cloud infrastructures. It is therefore crucial to ensure their effective and continuous operation. A vision to do this consists in the development of autonomous and adaptive management solutions, capable of dynamically and continuously reconfiguring these systems in order to maintain a desired state of operation in the face of unstable and unpredictable operational conditions. A main obstacle to the effective deployment of dynamic reconfiguration solutions is the lack of methods and means to ensure the effectiveness and safety of these dynamic con- figuration changes. The overall contribution of this thesis is to provide concepts, methods and tools to enable an online configuration verification. Our approach to build this framework was first to define a high-level language dedicated to the specification and verification of configurations. Second, we designed a generic flexible and adaptable runtime verification service, able to manipulate the concepts defined in this language. Finally, we defined an architecture of adapters for integrating existing systems and platforms. This allows our framework to support a runtime configuration verification process that starts at design time with a rigorous specification of configuration models and continues at runtime through automatic checking of configurations based on these models. The framework has been implemented in a prototype that has been experienced on a series of experiments from two different application domains: the verification of a messaging middle- ware's configurations in a JMX environment and the verification of virtual machines' configurations in a CIM/WBEM (DMTF standards) environment. The results showed the feasibility of our approach and the framework's ability to support a flexible and adaptable online verification of configurations that can be integrated with existing management solutions